They are teaching the turtles that this location is the new spawning
grounds. Its an investment in time. Years from now they will come back
to this same beach and spawn more. You can only change a breeding ground
by using babies, in this case turtles.
What gets me is that initial pause. The bird knows this song. He knows when the drum comes in. Being able to anticipate musical rhythm is a form of intelligence very few species have, and this is the most remarkable example of it I’ve ever seen in a bird. The cockatoo knew to wait for the drums.
rhythmic awareness: a prerequisite of language evolution
Glube Fics 